Quick checks for used amps

[white4d96]

I am planning on meeting a local seller who is going to trade me an MTX 81000d amp for my two Alpine S-10's plus my Power Acoustik amp plus $100. He said he would let me hook the amp up before deciding on the transaction. I was wondering if any of you guys had a procedure for checking the functionality of a used amp, something that preferably won't take too long and/or piss the guy off to the point of costing me extra money. Any ideas?

[cc_audio]

I use a power supply, a multimeter, and an MP3 player. The power supply is the greatest invention ever when buying and selling car audio. Mine is already rigged with wires and takes all of 5 min to hook up to any amp. I just use an MP3 player (loaded wit a 50hertz tone) with an RCA adapter to run audio input and use the multimeter to check AC output. Takes about 5-10 min tops to test any amp without being anywhere near a car or battery.

[white4d96]

I use a power supply, a multimeter, and an MP3 player. The power supply is the greatest invention ever when buying and selling car audio. Mine is already rigged with wires and takes all of 5 min to hook up to any amp. I just use an MP3 player (loaded wit a 50hertz tone) with an RCA adapter to run audio input and use the multimeter to check AC output. Takes about 5-10 min tops to test any amp without being anywhere near a car or battery.

transaction will be done by our cars I think so I will just hook it up to the battery. So check the AC output at 50Hz and see if it matches the RMS power?

[cc_audio]

transaction will be done by our cars I think so I will just hook it up to the battery. So check the AC output at 50Hz and see if it matches the RMS power?

If there's any AC output, chances are it works. Just check to see if it reacts when you turn the gain between 0 and 1/2 way. If the AC voltage seems to climb and decline consistantly with the gain, amp is probably good to go.

[white4d96]

If there's any AC output, chances are it works. Just check to see if it reacts when you turn the gain between 0 and 1/2 way. If the AC voltage seems to climb and decline consistantly with the gain, amp is probably good to go.

Alright awesome. Thanks for the help =]

[cc_audio]

No problem, good luck. Hope the amp works.

[ISO]

You want to ask to look at the circuit board, That ranks pretty high on my list of things to check out. Even for the novice you should be able to point out something that doesn't look rite pretty easy. (or something that looks weak and might fail latter.)

The seller should be more than happy to let you look at the board unless its a real hard amp to get into.

Use your nose, your nose can tell you alot about a circuit board so sniff around in there alittle.

I dealt with amps that with one wiff of the amp I didn't even have to open it up.

All you can do next is hook it up and when you do, don't hook anything up to the speaker outputs and have the gain and bass boost turnned all the way down and crossover all the way up since it doesn't sound like you have a woofer to check it out.

When you confirm that everything is fine, then put a load (DMM,Speaker,etc).

Don't hook it up with power on your lines so yank the fuse out of the power wire.

Edited October 20, 2009 by ISO

[ISO]

Forgot to tell you that once you know its powering up propperly you can play with the gains and bass boost.

[white4d96]

You want to ask to look at the circuit board, That ranks pretty high on my list of things to check out. Even for the novice you should be able to point out something that doesn't look rite pretty easy. (or something that looks weak and might fail latter.)

The seller should be more than happy to let you look at the board unless its a real hard amp to get into.

Use your nose, your nose can tell you alot about a circuit board so sniff around in there alittle.

I dealt with amps that with one wiff of the amp I didn't even have to open it up.

All you can do next is hook it up and when you do, don't hook anything up to the speaker outputs and have the gain and bass boost turnned all the way down and crossover all the way up since it doesn't sound like you have a woofer to check it out.

When you confirm that everything is fine, then put a load (DMM,Speaker,etc).

Don't hook it up with power on your lines so yank the fuse out of the power wire.

I have drivers to test with. My plan was to direct swap amps and test that way. And don't worry, I always disconnect my hot wire from the batt before messing with power connections (fuse blocks are...not the easiest to get at right now.)

[ISO]

I have drivers to test with. My plan was to direct swap amps and test that way. And don't worry, I always disconnect my hot wire from the batt before messing with power connections (fuse blocks are...not the easiest to get at right now.)

Sounds good man!

If you want to be extra careful and this trick is alittle over kill but is a good idea on really big amps (2000 watts and bigger). Before you connect the power you can use a test light to power up the capacitors in the amp before you hook up the power and turn it on.

EDIT: it stops that spark you see when you hook up an amp and in theory prevents shock to the amp itself.

Thats why the fuse block is nice and is how I do it. I use the test light there to charge the amps, then put the fuse in.

Same concept as chargeing a big capacitor.

I'm full of useless knowledge and you probably don't even need to do this just thought I would put it out there.

Edited October 20, 2009 by ISO